Project Title & Location

SR509 I-5 Freight & Congestion Relief Project in Burien, SeaTac, & Des Moines

Project Description
The SR 509/I-5 Freight and Congestion Relief Project will ease congestion on I-5, improve freight mobility, lower travel times, accommodate plans for a new south-oriented access to Sea-Tac International Airport, and increase safety on south King County roadways. In addition, the project includes several environmental improvements. The 2005 Transportation Partnership Account will fund continued design and right-of-way acquisition. The project may be constructed in phases depending on funding.

Contractor/Consultant
HNTB Corporation is prime design consultant.  Other consultants working on SR 509 include Carter Burgess, Jacobs and TBE

Recent Progress
Record of Decision signed by FHWA on March 20, 2003.  Access Point Decision Report approved by FHWA on April 17, 2003.  Received the ASSHTO National Value Engineering Honorable Mention Award for Most Value Added Proposal in July 2003.  Visual Guidelines completed in September 2003.  I-5 Access Hearing held on November 19, 2003.     Geometric and hydraulic design work is underway and on schedule.  For more information, please see the project web site:  www.wsdot.wa.gov/projects/I5DesMoinesWaySouth188St/

Design Construction Impacts
Design revision for the SR 509/ South Access (to Sea-Tac Airport) Interchange has been proposed and is being considered by the SR 509 Steering and Executive Committees.  If accepted, design revisions will be incorporated into the design file within the current schedule.   The 2003 Cost Estimate Validation Process (CEVP^TM)  for the entire SR 509 project estimates construction durations of six to eight years and $966 million additional funding needed.  Funding for the remaining right of way purchases and construction depends on additional funding from the Regional Transportation Investment District (RTID).   The Nickel Funding Package funds will be used by Jan. 2007.  If RTID funding is not received, work on the project will cease and total cost to complete will increase.

Environmental Impacts / Compliance
As part of the Nickel Funding Package, the SR 509 project will contribute up to $9 million to the construction cost of the Des Moines Creek Basin Plan projects and will use the facilities to help manage SR 509 storm water runoff.  This construction is expected to start in late 2004.    For the entire SR 509 project, permit applications are being prepared.  Wetland impacts have been reduced to less than ½ acre.

Impacts to Traffic

When complete, the SR 509 project will reduce congestion on I-5, reducing travel times by up to 15 minutes between Seattle and Tacoma.  The project will give commuters a choice of routes, thereby reducing trip distances and trip times. The new route provides direct freight access between Kent, the Port of Seattle and the Duwamish industrial area.  Airport access from the south will be improved, reducing traffic impacts on local streets and I-5.

During construction, four lanes of I-5 will remain open in the peak direction during the peak hours.  

City of SeaTac is project lead.  Nickel Funding Package provides funding for IB4 for reprofiling SR 99 at the proposed SR 509 undercrossing.

Planned vs. Actual Expenditures
(Total Project Cost)

Nickel funds included in above costs

2005 Transportation Partnership Account